Manual grinders aren't bad, unless you go for the cheap ones. For example, my Comandante grinder has a steel conical burr, but most of the cheaper ones come with ceramic. The thing is, the thing's sharp, I could actually cut myself if I wasn't careful during cleaning, opposed to the ceramic burrs that are pretty blunt (from what I've heard, never had one). That makes grinding coffee a breeze (maybe 20-30secs for ~13grams for a cup of coffee), even on finer settings, also it introduces less dust, as it doesn't crush the beans but cuts them into fine bits. There are many models of manual grinders that come with great burrs, some of are of the Chinese make if price is an issue (1zpresso for example).

Flat burrs are an electric grinder thing. The mechanics of grinding with those is a little different than with conical ones, but the result is pretty much the same. Electric grinders can come with both conical or flat burrs. I've got an absolute overkill of a grinder meant for commercial use, bought used for around $300. The thing is a beast, takes less than 5secs for ~20g of coffee. I wouldn't suggest you get one (Mazzer Super Jolly FYI), just because of its size, but anything with that kind of build quality is likely gonna last you a literal lifetime. There are some more reasonably sized consumer electric grinders though, I heard Wilfa Svart is decent, some other might be fine as well.